Drill mine



Nov. 17, 1959 R. D. MATTINGLY El'AL 2,

DRILL MINE Filed April 26, 1957 i V F n Hill m m INVENTORS R. D. MATTING LY BY F. E.BU1 'LER Y Ma 2&

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Patented Nov. 17, 1959 DRILL MINE Robert D. Mattingly, Beltsville, Md., and Francis E. Butler, Washington, D.C., assignors to the United States g America as represented by the Secretary of the Application April 26, 1957, Serial No. 655,451

1 Claim. (Cl. 10210) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to drill mines of the submarine type. More specifically the invention relates to a submarine drill mine of the bottom type particularly suitable for planting in shallow water and which upon actuation of the firing mechanism makes a signal on the surface of the water to indicate that the mine has been actuated.

Heretofore submarine drill mines of the bottom type have been standard service mine casings to which a kit containing a signal and a recovery float were attached. While satisfactory for the larger mines, adaptation of these kits to smaller shallow Water mines, such as those adapted to be laid by aircraft, resulted in a signal of small size and a recovery float of insuflicient bouyancy. Attempts were also made to adapt the service mine casings of the small aircraft laid shallow water bottom mines by fabricating wells in the casing and using the extender well to house the signal and recovery float. These attempts required the use of either non-service type mine casings or extensive redesign of service casings. Use of wells, however, not only resulted in small signals and floats but also resulted in decreased reliability on mud or silt bottoms.

Split mine casings having an instrument section which acts as an anchor. and an explosive chamber to be used as a moored float which would rise to the surface upon actuation of the mine have also been considered. Drill mines of this type, however, ofler serious design and development problems such as the design problems involved in orienting such a mine after entry into the water.

It is therefore an object of the present invention to provide a submarine drill mine of the bottom type which is small enough for laying by aircraft and which upon actuation gives a large signal visible by day or night.

Another object is to provide a reliable submarine drill mine of the bottom type which will function in shallow water on mud or silt bottoms.

A further object is to provide a submarine drill mine of the bottom type adapted for laying by aircraft in shallow water which utilizes only standard service mine casings and components.

A still further object is to provide a submarine drill mine of the bottom type which upon actuation of the firing mechanism releases a gas which rises to the surface of the water where it spontaneously ignites to form a flame and smoke signal to indicate the location and actuation of the mine.

Other objects and the attendant advantages of the invention will become apparent to those skilled in the art as the invention is more fully disclosed in the following detailed description in conjunction with the accompanying drawing which is given by way of a constructional example of one practical embodiment of the invention.

The single figure is a sectional view of a typical bottom type submarine mine designed for laying by aircraft in shallow water.

The above objects are achieved in accordance with the invention by inserting in a standard type of mine casing, in that portion normally occupied by the main explosive charge, a charge of chemicals which upon reaction with water will form a gas which in turn will spontaneously ignite when exposed to the air in the atmosphere at the surface of the water so as to form a bright flame and a large volume of smoke. The charge of water reactive chemicals is sealed in the watertight mine casing until the exploder mechanism of the mine is actuated. The mine casing is then ruptured in some suitable manner such as by the explosion of the standard mine booster charge. The surrounding water then enters the casing and reacts with the water reactive chemicals to form a combination of gases. These gases rise immediately to the surface of the water where in contact with the air they spontaneously burst into flame indicating the location and actuation of the mine.

Referring now to the figure of the drawing the typical cylindrical ground mine casing 10 is composed of an instrument section 11 and an explosive section 12. The instrument section 11 contains the standard detection apparatus, clocks, firing mechanism and power supply. These latter may be of any desired type many of which are well known and which do not form the subject matter of the present invention. Located in wells fabricated in the exterior surface of the casing are the standard safety and arming devices such as the hydrostatic switch 13 and the extender mechanism 14 illustrated. The construction of these devices is also well known and does not form the subject matter of the subject invention.

The explosive section 12 consists of a cylindrical casing of the usual type attached to the instrument section 11 in the manner well known in the art. Located in the end of the explosive section adjacent to the usual firing mechanism of the instrument section 11 and the extender mechanism 14 is the standard booster explosive 15. The major portion of the explosive section 12 is filled with the water reactive chemical charge 16. As shown in the drawing a thin weakened wall 20 is disposed between the booster explosive 15 and the chemical charge 16. Portions of the explosive section 12 may also be filled with an inert material such as sand 17. The proportions of inert material and water reactive chemicals may be varied depending on the size of the casing, the amount of water reactive chemical desired, etc. The explosive section 12 is provided with the usual opening 18 through which the water reactive chemicals and inert materials are loaded. This opening 18 is provided with a cover plate 19 provided with the usual seal to make the casing watertight.

The Water reactive chemical charge which has been found best suited for use in the drill mine of the present invention is a homogeneous mixture of particles of calcium phosphide and magnesium-aluminum phosphide. The magnesium-aluminum phosphide reacts with water to produce a gas known as phosphine which when ignited in air burns with a bright flame and produces a large amount of smoke. The calcium phosphide reacts with water to produce a combination of gases one of which, bi-phosphine, ignites spontaneously upon being exposed to air. Thus upon actuation of the mine the phosphides react with the water after the mine casing is ruptured. The resulting phosphine and bi-phosphine gases rise to the surface of the water where the bi-phosphine spontaneously ignites and in turn ignites the phosphine which burns to form the flame and smoke signal.

Regulation of the size of the particles of phosphide is important in producing the signal. Where the particles are too large, too little gas is produced over too long 3 a period of time to provide an adequate signal. If the particles are too small the gases produced may be dissipated in a very short period before an adequate signal is produced. For best results the magnesium-aluminum phosphide should be approximately A to /2 inch in length. About 20% dust may be tolerated. The particles of calcium phosphide should be of such size that 30% will pass a No. 4 sieve and rest on a No. 8 sieve, 60% pass a No. 14 sieve and rest on a No. 200 sieve. The remaining should be in the form of dust so that it will react instantaneously with the water thus producing suflicient bi-phosphine gas to cause immediate ignition of the phosphine gas at the surface of the water.

As low as 20% calcium phosphide may be utilized in the phosphide mixture where favorable conditions such as warm temperatures and calm sea and wind conditions prevail... Mixtures containing higher percentages of the calcium phosphide are to be preferred, however, since the higher percentage of calcium phosphide produces a more ignitable gaseous mixture and are therefore considered to be more reliable.

Phosphide mixtures containing 50% calcium phosphide have been found to give excellent results both as to ignitability and as to the amount of smoke produced. A quantity of 35 pounds of this phosphide mixture has been found to give a smoke signal 40 feet wide and 60 feet high under calm sea conditions from a 35 foot water depth. Seventy-three pounds of the mixture has been found to give a smoke signal 60 feet wide and 200 feet high from the same depth under similar conditions.

The calcium phosphide which is employed in the phosphide mixture of the invention must be of high quality. It is best produced by heating slaked lime and red phosphorous in a crucible which is divided into an upper and a lower compartment by a perforated divider. The slaked lime is placed in the upper compartment and heated to a red heat. This results in the volatilization of the phosphorous placed in the lower compartment by radiation. The calcium phosphide resulting from this process appears'to have the formula Ca P and'to react with water to form bi-phosphine (hydrogen hemiphosphide), P H in accordance with the following equation:

Ca3P2+ 3 Ca i: 2+P2H4L+ Hz the bi-phosphine (hydrogen hemiphosphide) P H is spontaneously ignitable when exposed to air.

the pure calcium phosphide appears to produce the biphosphine which spontaneously ignites upon exposure to air and which is necessary for the drill mine signal of the invention.

Commercially available magnesium-aluminum phosphide Mg P ZALP may be employed in the phosphide mixture of the invention so long as the phosphides are reasonably pure. The reaction of water with the magnesium-aluminum phosphide is believed to proceed as follows:

It is important that the calcium phosphide be pure since only ture and split the mine casing depends upon many variable factors. It is desirable to split the mine casing to expose the phosphides to the water and yet maintain a minimum dispersion of the phosphides. It is also desirable to maintain a degree of confinement of the phosphides since some confinement of the phosphides is necessary to keep the heat of reaction at a sufiiciently high level to produce large quantities of gases within a short period. The explosive charge therefore should split the casing but not scatter the phosphides. In the standard aircraft laid shallow water bottom mine one pound of Comp B has been employed With good results.

The phosphide mixture may contain other chemicals to produce difierent colors or effects. For example, calcium carbide may be mixed with the phosphides. This carbide reacts with the water to produce acetylene which when ignited burns with intense light.

The drill mine of the present invention may be laid by aircraft, surface vessels and submarines in the same manner as are service mines. The drill mines may be actuated in any of the many means well known to those skilled in the art such as by acoustic and magnetic sens ing devices, by contact firing devices or they may be used in controlled minefields.

From the foregoing it is apparent that there has been provided a drill mine of the submarine bottom or ground type which upon actuation produces a signal of high visibility and luminosity on the surface of the water. The mine uses only standard service mine casings which are adapted for laying by aircraft and yet produces a satisfactory signal which is easily and economically produced.

It is understood, however, that the invention may be adapted for any type of submarine ground mine for use in shallow water and that any means used to explode submarine mines may be used to explode the charge of the drill mine of this invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

A submarine drill mine of the type adapted to rest on the bottom for use in shallow water comprising a cylindrical elongated hollow watertight ground mine outer casing, a charge of chemicals comprising calcium phosphide and magnesium-aluminum phosphide disposed within one end portion of said casing, said chemicals being such as to react vwith water to produce a gaseous mixture which spontaneously ignites and burns on exposure to air, said casing having a weakened wall housing said chemicals at said one end portion, a charge of explosives adjacent said wall within the center portion of said casing just sufficient upon ignition thereof to rupture said; wall and outer casing so as to allow water to enter said casing and react with said charge of chemicals and to allow the gaseous mixture so produced to escape from said casing while the casing rests on the ground, and means at the other end of said casing to ignite said charge of explosives.

References Cited in the file of this patent UNITED STATES PATENTS 

